In this compilation we present the first occurrences of 22 vascular plant species not previ ously documented from the territory of Hungary. Fifteen of the species are casuals, while seven of them are already naturalised, at least locally. We report the mass appearance and naturalization of Sagina maritima and the emergence of Carduus pycnocephalus along roadsides, single sites of Chaenorhinum litorale and Solanum elaeagnifolium near railway lines, and the localities of Lepidium latifolium and Sisymbrium volgense in various disturbed habitats, and some occurrences of Acalypha virginica in ur ban environments. The first record of Bacopa rotundifolia is from a rice field, while that of Hydrocotyle sibthorpioides is from an urban lawn, and Senna tora occurred on construction debris. Among the spe cies that appeared spontaneously as a result of earlier planting, Celastrus orbiculatus forms a natural ized population in a tree plantation, Hygrophila triflora and Pontederia cordata are present in artificial canals and lakes, and Cenchus longisetus has become naturalised and is spreading along the banks of the Danube in Szentendre. Most other species are associated with trampled or heavily disturbed habi tats in built-up areas (pavement edges, fences, ruderal areas). Alnus cordata, Eryobotria japonica, Euon ymus alatus, Paxistima canbyi, Pistacia terebinthus and Solanum pseudocapsicum are present as casuals, while Viola palmata has become naturalised in built-up environments. The naturalisation process of Allium aflatunense on a private property has also been documented.